You have looked at the score at the bottom of the page, noticed that it is quite high and wondering how on earth a Sudoku package could possibly be rated so highly. The answer is that it isn't the Sudoku that holds our interest, it's the rather well hidden mode of picture puzzle that has us gripped, otherwise known as picross.

For those who haven't played 'Picture Puzzle' before, the concept involves rows and columns, each of which has a series of numbers indicating how many squares need to be filled in. There are certain rules that have to be followed- if there are only 5 and 2 black squares in a row, there has to be at least one square gap separating them and you have to make sure that the right number of squares are coloured in for each coloumn. The game can be played either with the buttons or the stylus, acting like a pen doing a paper version of the puzzle. For the most part, the stylus is fine although it can be a little oversensive, filling in squares accidentally but there are buttons available to wipe out any mistakes.

Each puzzle is set against the clock and the speed at which it is completed determines whether you get a 'Must Try Harder', 'Well Done' or 'Extremely Well Done' and your ratings can be accessed in the form of a grid. Completion of a grid forms a picture with a description of what it resembles, although there are times when the finished picture rarely resembles the object it is meant to represent. The way the game is structured is also far better than that of other Picross titles: puzzles are bundled together in blocks of 100 each starting with the easier difficulty level and getting increasingly difficult so if you get stuck on one block, you can switch to another, rarely leaving you stranded in one place for too long.

It isn't quite as beginner friendly as Nintendo's take on Picross- there isn't a tutorial to show you how to play the game and there isn't a hint system to help you out-neither does it have fancy animations upon completing a puzzle, but it does have one trump card over the official game and that's colour. It may sound daft, but the addition of colours gives the game a whole new dimension. Being able to fill in squares with yellow, black, green, red and blue colours makes the puzzles more interesting and also makes playing strategic- if only two rows have red squares, then you can then work out where the rest of the colours go as opposed to just relying on the counting method required for working out single coloured puzzles.

Of course, it wouldn't be a proper review without us mentioning the mainstay of the bundle, the Sudoku mode. Sudoku involves putting the numbers 1-10 in each row without repeating the same number and all columns have to inlcude 1-10 before the puzzle is complete. Like Picture Picross, there are 1000 puzzles in all so if Sudoku is your thing, there's plenty here to get your teeth into. As Sudoku goes it's okay but nothing to rave about- you have to use the stylus to write the numbers on the screen and for some reason the game has issues with the number 7, turning it into 5 on a regular basis which is frustrating but it does the job sufficiently well even if it's a little lacking in presentation and doesn't have any game modes to try and make the concept more interesting.

Conclusion

Essential Sudoku is, quite literally, an essential purchase for your DS collection. It may lack polish and have a slightly clumsy interface but the wide range of picross puzzles here mean that there is hours of compulsive puzzling entertainment at your fingertips. and considering you can buy the game for around £10-15 brand new, it's something of a bargain. Even now with over a year of playing the game on and off, I have only solved around 400 of the available picture puzzles and still have a staggering 600 to go.

With a thousand puzzles to solve, you would be hard pressed to find another cartridge with quite so much value for money. And of course, there's always Sudoku...